Polysilicon wafers used to produce solar batteries are manufactured by producing a polysilicon ingot of a quadratic prism, cutting out from the polysilicon ingot a multitude of polysilicon blocks each in the shape of a quadratic prism by the use of a bandsaw, etc., and further by slicing each polysilicon block into quadrangular plates.
When the bandsaw is used upon cutting out the silicon blocks from the silicon ingot, surfaces of the blocks might be damaged, and if silicon wafers are produced without removing such damaged parts, there arises a problem that cracks might occur in the following processes after the production of the silicon wafers, resulting in a reduction in the yield of the products. Accordingly, the side surfaces of the silicon blocks are mechanically polished (see, for example, a first patent document).
First patent document: Japanese patent application laid-open No. 2004-6997